I just discovered feathersjs and really like the idea behind it, even though I'm still unsure how the service-based philosophy can fit for applications which are more complex than a simple CRUD UI.
In order to better understand it I made up an example: Consider an application where you can create and share surveys. You could easily manage to create a survey service to create, update and get the properties of a survey (i.e. questions and answers). But how should one handle the following aspects:
1) There are actions, i.e. service invocations which do not affect the data at all. One action could be to send a reminder email to all invited users who did not participate on a survey yet. If not using feathers I would created a dedicated express endpoint for this, but how do those actions fit in the feathers philosophy? Should one create a service (only implementing one HTTP verb) per action? This will get confusing soon. Use hooks that detect updates on virtual fields and trigger the action? Hard to document and confusing as well.
2) Imagine users could add comments to a survey. The comments would be part of the survey model (I'd use MongoDB for that, so consider each survey object to have a comments array). The client web would invoke the GET /survey/123 method on the survey service which would return the comments amongst the other properties (question, answers, ..). But what about adding comments? Should I use a dedicated service for it, or how would this fit into the survey service? How would such a request look like?
From the Feathers slack channel: https://feathersjs.slack.com/messages/C0HJE6A65/
Sending an email is fine in a hook. For actions you could do a patch with a certain action attribute and then use hooks to determine which action should be performed, etc. The other way would be a simple small service that only has create implemented. For comments I would probably have a comments or survey-comments service and then your survey/123 could populate the comments. Or the web could make 2 calls, one to fetch the survey, the other to fetch the comments.